Vinegar production from vegetable waste: Optimization of physical condition and kinetic modeling of fermentation process

Abstract

Vegetable waste, as a low cost natural product, has been used as a source of vinegar production. In the present study, the physical conditions for fermentation by Acetobacter aceti (NCIM 2116) have been optimized and fermentation kinetics of the acetification has been studied in a batch system. The highest acetic acid production of 5.98% occured when pH is 6.2, temperature was 30°C and time is 90 h. Analysis of eigen values predict pH is the most significant factor for production. FTIR study confirmed the presence of C=O, O-H, N-H, CH₃, CH₂ groups in acetic acid. A simple kinetic model has been suggested using logistic equation for growth and the Luedeking - Piret equation for vinegar production and substrate utilization. The model parameters are μ_m= 0.0554 h^-1, α= 3.3903 g/g of biomass, β= 0.0219 g/g of biomass.h^-1, S₀=70.538 g/L. A significant inhibitory effect of accumulation of acetic acid on growth of A.aceti has been found. It is presumed that end product limits growth by acting as an uncoupling agent.